FastAPI / Modern Python API

When to use this skill

• Building high-performance APIs with FastAPI.
• Defining Pydantic models.
• Structuring API projects.

1. Structure

• Routers: Split routes into modules (app/routers/users.py) and include them in main.py.
• Dependencies: Use Dependency Injection (Depends()) for DB sessions, auth, and shared logic.

2. Pydantic Models

• Separation: Create separate models for Input (UserCreate), Output (UserResponse), and Database (UserDB).
• Validation: Use strict Types and Field(...) for validation metadata.

3. Async

• Def vs Async Def: Use async def for endpoints that await I/O (DB, HTTP). Use def only if blocking CPU.